linux-kernel - Re: [PATCH v4 2/2] watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by

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Date: Fri, 9 Feb 2024 14:43:39 -0600
From: Sam Protsenko <semen.protsenko@...aro.org>
To: Peter Griffin <peter.griffin@...aro.org>
Cc: arnd@...db.de, krzysztof.kozlowski@...aro.org, linux@...ck-us.net, 
	wim@...ux-watchdog.org, alim.akhtar@...sung.com, jaewon02.kim@...sung.com, 
	alexey.klimov@...aro.org, kernel-team@...roid.com, tudor.ambarus@...aro.org, 
	andre.draszik@...aro.org, saravanak@...gle.com, willmcvicker@...gle.com, 
	linux-fsd@...la.com, linux-watchdog@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v4 2/2] watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by_phandle()
 for PMU regs

On Thu, Feb 8, 2024 at 10:21 AM Peter Griffin <peter.griffin@...aroorg> wrote:
>
> Obtain the PMU regmap using the new API added to exynos-pmu driver rather
> than syscon_regmap_lookup_by_phandle(). As this driver no longer depends
> on mfd syscon remove that header and Kconfig dependency.
>
> Reviewed-by: Sam Protsenko <semen.protsenko@...aro.org>
> Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
> ---

Tested-by: Sam Protsenko <semen.protsenko@...aro.org>

Tested on my E850-96 board (Exynos850 chip) with Debian rootfs. Test procedure:

1. Added this to /chosen node in dts:

    bootargs = "s3c2410_wdt.tmr_atboot=1 s3c2410_wdt.nowayout=1
s3c2410_wdt.soft_noboot=0";

2. Check if watchdogs are active:

    # dmesg | grep watchdog
    [    1.488149] s3c2410-wdt 10050000.watchdog: starting watchdog timer
    [    1.489003] s3c2410-wdt 10050000.watchdog: watchdog active,
reset enabled, irq disabled
    [    1.496928] s3c2410-wdt 10060000.watchdog: starting watchdog timer
    [    1.502984] s3c2410-wdt 10060000.watchdog: watchdog active,
reset enabled, irq disabled

3. Generate a panic to cause wdt reset:

    #  echo c > /proc/sysrq-trigger

In 15 seconds (wdt timeout) reboot happens, and bootloader shows this
message for the reboot reason:

    Watchdog or Warm Reset Detected

That proves regmap works fine with this patch. Otherwise reboot wouldn't happen.

>  drivers/watchdog/Kconfig       | 1 -
>  drivers/watchdog/s3c2410_wdt.c | 8 ++++----
>  2 files changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 7d22051b15a2..d78fe7137799 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -512,7 +512,6 @@ config S3C2410_WATCHDOG
>         tristate "S3C6410/S5Pv210/Exynos Watchdog"
>         depends on ARCH_S3C64XX || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
>         select WATCHDOG_CORE
> -       select MFD_SYSCON if ARCH_EXYNOS
>         help
>           Watchdog timer block in the Samsung S3C64xx, S5Pv210 and Exynos
>           SoCs. This will reboot the system when the timer expires with
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 349d30462c8c..686cf544d0ae 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -24,9 +24,9 @@
>  #include <linux/slab.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
> -#include <linux/mfd/syscon.h>
>  #include <linux/regmap.h>
>  #include <linux/delay.h>
> +#include <linux/soc/samsung/exynos-pmu.h>
>
>  #define S3C2410_WTCON          0x00
>  #define S3C2410_WTDAT          0x04
> @@ -699,11 +699,11 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>                 return ret;
>
>         if (wdt->drv_data->quirks & QUIRKS_HAVE_PMUREG) {
> -               wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
> -                                               "samsung,syscon-phandle");
> +               wdt->pmureg = exynos_get_pmu_regmap_by_phandle(dev->of_node,
> +                                                "samsung,syscon-phandle");
>                 if (IS_ERR(wdt->pmureg))
>                         return dev_err_probe(dev, PTR_ERR(wdt->pmureg),
> -                                            "syscon regmap lookup failed\n");
> +                                            "PMU regmap lookup failed.\n");
>         }
>
>         wdt_irq = platform_get_irq(pdev, 0);
> --
> 2.43.0.594.gd9cf4e227d-goog
>